Pelagic clay and Mn nodules from DOMES sites in the North Pacific and a varved glacial lake deposit from Connecticut were analysed for Os concentration and isotopic composition by isotope-dilution secondary ion mass spectrometry after treatment by NiS fusion or oxalic acid leaching. Bulk pelagic clay from DOMES site C has 187Os/186Os = 6.5 and Os = 0.14 ng/g. Oxalic acid leaches of this same sediment and of Mn nodules from DOMES sites A and C have more radiogenic 187Os/186Os ratios which average 8.3. Bulk glacial Lake Hitchcock sediment has 187Os/186Os = 12.5 and Os = 0.06 ng/g. The total Os flux to North Pacific pelagic clay is 7 to 10 ng Os/cm2/106 y. Lake Hitchcock sediment provides an integrated value for the local crustal 187Os/186Os ratio. The oxalic acid leaches are assumed to attack hydrogenous phases selectively. A simple model in which the only sources of Os to the ocean are continental crust with the isotopic composition of Lake Hitchcock (187Os/186Os = 12.5) and extraterrestrial particles with 187Os/186Os = 1.1 results in a cosmic flux of osmium to the sediment of 4.9 ng Os/cm2/106 y of which 20% is hydrogenous. A model in which the sources of Os to the ocean are continental crust with an 187Os/186Os ratio of 30 (from the model of Palmer and Turekian, 1986), oceanic mantle or crust with 187Os/186Os = 1.04 and extraterrestrial particles with 187Os/186Os = 1.1 results in a cosmic flux of Os to the sediment of 5.7 ng Os/cm2/106 y of which none is hydrogenous. These extraterrestrial Os fluxes correspond to maximum C-1 chondrite accretion rates of between 4.9 × 104 and 5.6 × 104 tonnes/y.

From 1983 until 1989 NOAA-NCEI compiled the NOAA-MMS Marine Minerals Geochemical Database from journal articles, technical reports and unpublished sources from other institutions. At the time it was the most extended data compilation on ferromanganese deposits world wide. Initially published in a proprietary format incompatible with present day standards it was jointly decided by AWI and NOAA to transcribe this legacy data into PANGAEA. This transfer is augmented by a careful checking of the original sources when available and the encoding of ancillary information (sample description, method of analysis...) not present in the NOAA-MMS database.

Supplement to: Esser, Bradley K; Turekian, Karl K (1988): Accretion rate of extraterrestrial particles determined from osmium isotope systematics of Pacific Pelagic clay and manganese nodules. Geochimica et Cosmochimica Acta, 52(6), 1383-1388